A dynamic model for a high-volatile solid fuel fired bubbling fluidized bed boiler is presented. The model consist of an air-flue gas model which includes a furnace model describing combustion in a bubbling fluidized bed and a model for a water-steam circuit describing heat transfer from hot flue gases to water and steam. The versatile furnace model takes account of quality parameters of fuel so that the effects of moisture; particle size; heat value; and the amount of volatiles can be simulated. The model is based on the first principles mass; energy; and momentum balances. Results from validation of the model against a bubbling fluidized bed boiler process data are presented. The validation showed that the model can describe the dynamics and static gains of the process very well.